Tracking functions are conventionally implemented by using a servo system to position or spatially orient a sensor so that it may receive signals from a target of interest. An error signal is generated when there is a discrepancy between the measured and desired sensor orientations. The error signal is used to drive a controller, which in turn generates signals to move the servo system and sensor toward the desired spatial orientation. As the sensor is moved toward the desired orientation, the pointing error is reduced.
There are targets of interest that one would like to track where a direct measurement of target position or orientation is difficult or impossible. In these cases, a conventional tracking system that uses a direct measurement of position error to drive a servo system may be of little use. One such target of interest is a plume or puff of gas moving in turbulent wind conditions.
It is, however, often possible to measure some property of the target, or its surrounding environment, and use this information to track the target. When attempting to track a target, such as a plume or puff of gas in turbulent wind conditions, the method used by the present invention has significant advantages.